In the following days, people from every state - and almost every single district - of America helped at Ground Zero - rescuing casualties, digging up bodies, cleaning up and rebuilding.

Now they are paying a high price for their selflessness - while most of the world remains oblivious to their suffering.

Over 2,000 first responders - anyone who helped out at Ground Zero, including building workers, electricians, doctors and paramedics - have died from illnesses caused by breathing in the toxic fumes that engulfed the site in the weeks after the terror attack.

As thousands more currently battle 9/11-related diseases such as cancer or severe respiratory disease, shockingly, it's predicted that by the end of this year the number of first responders who have died since the tragic event will overtake the number who died on the day.

Darren Stach's father Joseph Stach died from 9/11 related cancer earlier this year.

Number of deaths since set to overtake those from on the day

Lawyer Michael Barasch, who represents those fighting for the benefits and compensation, says his office is getting around 30 new 9/11-related cancer cases a week:

“We're representing hundreds of local residents and pupils - as well as people from all over the world, who were working in the area at the time.

“I predict that by the end of this year the number of first responders who died since 9/11 will overtake the number of first responders who died on the day.”

What's more, 15 men who were near the World Trade Center on that fateful day have been diagnosed with breast cancer - a type of cancer where 99 per cent of victims are women. Five of them were first responders, including an NYPD sergeant, two firefighters, an iron-worker and a highway repairman.

Many 9/11 cancer sufferers have had to undergo brutal procedures to stem the spread of the aggressive diseases - such as having their tongues cut out and breasts removed.

Other heroes were plunged into poverty, no longer able to work and without adequate healthcare coverage.

Now after a lengthy campaign for benefits and compensation, 83,000 people have been enrolled in the World Trade Center Health Program, which offers care to those suffering from a 9/11-related illness - half of who are battling not one but two diseases such as cancer, PTSD or severe respiratory disease.

Deadly cocktail of poisonous air

After the two planes struck the Twin Towers on September 11, 2001, fires stoked by jet fuel raged for 99 days - spewing a cocktail of carcinogenic poisons - including asbestos, benzine, chromium and lead - into the Manhattan air.

Eager to show they would not be defeated by terrorism, authorities re-opened the area around Ground Zero days afterwards - mistakenly declaring the air safe.

It was only after the death of first responder firefighter James Zadroga in 2006, and an autopsy found his lungs were filled with glass and a host of carcinogenic substances related to Ground Zero, that scientists were able to link respiratory disease with 9/11.

Since then they have linked 68 cancers with World Trade Center toxins.

After a long fight, a 2010 bill passed in James’s name now promises healthcare and financial aid to those affected.

But chillingly, for those first responders who are still healthy - it’s not a case of if they will become sick but when.

'It was like having your mouth wrapped around an exhaust pipe'

Tom Wilson, 49, NYPD, had to have his tongue cut out

Tom spent days on search and rescue duty followed by weeks at Fresh Kills landfill site in Staten Island sifting through rubble from the Twin Towers looking for human remains.

“It was like having your mouth wrapped around the exhaust pipe of a motor vehicle,” he told Sun Online.

“It was a metallic acidic smell it was hard to describe but you could feel it burning your mouth and lungs as you breathed in and out.

“We ate and slept down there and in the beginning we got no protective gear.

“But back then we all thought the cough was temporary - we had no idea what was in store."

In 2008, dad-of-five Tom was diagnosed with aggressive tongue cancer and had to have a third of his tongue cut out, his neck dissected to remove lymph glands, skin grafts and a gruelling course of radiation therapy which left him with necrosis of the jaw, which means it's starved of blood.

Once a fit and healthy weight-lifter who loved to play sports, Tom now struggles to play-fight with his young kids in case they hit his jaw, he also suffers fatigue and can’t talk for long-periods.

Yet Tom, who still works as a police officer for Suffolk County Police Department, Long Island, claims he is one of the lucky ones.

“Many 9/11 responders are retired or deceased but I’m still working, I’m still a police officer,” he said.

Tom and his family during their campaign for better support for 9/11 first responders

“I’ve been a police officer for almost 24 years now and when I work with young police officers a lot of them were young children when 9/11 happened and they really have no understanding.

“But I don’t have any bitterness. I was caught up in an epic event and when I look back on it I’m very proud of my service.”

'He ditched his car and commandeered a bus to get down to Ground Zero'

Joseph Stach, firefighter, died from 9/11-related pancreatic cancer

New Yorker Darren Stach was only 12 on 9/11 but he can still vividly recall seeing his firefighter father Joseph returning from a 72-hour shift at Ground Zero, covered head to toe in dirt and dust – and with a cough that never went away.

“He was down there for the first 72 hours straight. At one point we didn’t know what his status was because he had missed one of the check-ins. He actually had fallen asleep because he literally had worked round the clock.

“The first time I saw him in our doorway, covered in dirt and dust, it was a shocking image. I can still see the look in his eyes now.”

Joseph recalls how his dad was “never the same person” after 9/11 but because he was a “tough guy” continued to work as a firefighter - through excruciating pain - until he was finally diagnosed with Stage 4 cancer in 2017.

Joseph was serving in Engine 48/ Ladder 56 of the New York Fire Department in the Bronx on 9/11

As well as Darren, Joseph left behind his wife JoAnn and four other children Corrin, 22, Kayla, 21, Ryan, 19 and Tyler, 18, when he passed away in January this year, aged 51.

“It’s really shocking for me that one of my parents has passed away so young - it’s definitely not something I ever thought I’d be dealing with at this age," they said.

“I’m engaged and I would have loved for him to be at my wedding. My youngest sibling is graduating from high school this year. These are pretty sad milestones he is going to miss.”

Making an emotional first visit to the Ground Zero memorial, a tranquil fountain on the site of the two Twin Towers, Darren clutched a photo of his father and urged the world not to forget the sacrifice people like his father had made.

'They're dying around us'

“I think outside of New York and New Jersey - not many people know about this issue,” he said.

“People in California or Texas have no idea how many people are still dying and how 9/11 is still affecting us out here.

“You know everyone’s flocking to see the new Avengers movie – but we have our real life superheroes who actually save our lives – like my dad – dying around us.

“It would be just be nice if the rest of the country and the world paid a little more attention to this.

“I got up and ran to him and just laid on top of him begging me to take me with him."

Now as well as dealing with intense grief at losing her “one true love” mum-of-four Brandi has been left with "nothing" - and has been embroiled in a long battle for the pension and benefits she deserves.

She wishes the world knew more about the plight of 9/11 first responders.

“I would scream off the rooftops if I could," she said. "It’s a worldwide disgrace.

“It’s now 13 months and nothing. They offered me $364,000 [£270,000] but if I took it I had to pay back the medical bill which was $850,000 [£632,000] for his mouth surgery and $1.8m [£1.3m] for chemo, plastic surgery and radiation. If I took it I owed them money.

“It took them 10 months for them to agree to give me three quarters of his pension but still no cheque.

“They said I can’t have his life insurance because his death certificate did not have 'line of duty' death and accidental death, they said I get no survivor benefits because they lost his paperwork which I have certified copies of.

“Nothing for me or the kids. They make it out to the world we are taken care of but we all have nothing and fighting a bitter battle.

“All the medics' wives are in the same position.”

One hero's battle for compensation

John Feal has been to over 178 funerals for first responders who lost their battle against what he calls the “toxic demon” of 9/11 cancer.

He was an early responder at Ground Zero from the 12th to 17th of September – when 3,000 pounds of steel crushed his left foot.

Despite undergoing surgery hundreds of times, having a kidney removed and donated to a fellow 9/11 responder and suffering PTSD, John has dedicated his life to fighting for benefits for his fellow responders.

Since 2005 he has made over 249 trips to Washington DC and had over 1,100 meetings with members of Congress in the Senate.

“I take this personally,” John, 51, said. “These people were warriors on 9/11, they were patriots. They went home to live a normal life and then they were hit by cancers, pulmonary fibrosis and other diseases.

“At first no one believed this was caused by 9/11. They tried to demonise us and knock us off course but we kept fighting.

“I started fighting for my own benefits, got them and then started helping others to get theirs.

“I just thought of that saying ‘there’s always somebody worse off than you’. Yeah I lost half a foot but these people all had invisible diseases - they had to prove it.

“In 2005 I started a foundation - the Feal Good Foundation to help people affected by this. I won’t accept no for an answer - especially not when I know something is right and human life is at stake.

“Since 2005 I’ve helped pass nine bills for those affected by 9/11.

“But there’s always more to be done this is not an issue that is going away.

“The impact is real. The impact is going to last until the last 9/11 responder dies. This is a generation-long epidemic.”

John’s pride and joy is a park in his hometown of Nesconset, Long Island.

Donated to him for $1, the park is a poignant memorial to all those first responders who died as a result of 9/11 illness.

A 6ft tall, 60ft black granite wall lists all the names of the brave men and women who have died.

Every year the Saturday after 9/11 John holds a service in which he reads out all the names of the dead.

CA-SCARY ISLANDS

TENER-GRIEF

But as thousands of individuals battle disease and thousands of others grieve for their loved ones who have lost their fight against the “curse of 9/11”, their message is not one of anger or resentment.

Darren, still mourning the loss of his beloved dad, said: “If could ask anything of of the rest of the country and the rest of the world it’s when you're going to the movies and rushing to see superheroes on screen, just remember that you're walking amongst heroes every day who have sacrificed their lives for our safety and our happiness. These are the real heroes.

“Never forget that my dad sacrificed his life - and even on his deathbed in the hospice he said he wouldn't change anything.